Charge air management system for automotive engine

ABSTRACT

A charge air management system for an automotive engine provides air charge densification and cooling during periods of operation at higher load. Two air ducts are provided, with a first for furnishing uncooled and unboosted air, and with a second duct for furnishing chilled and boosted air, with the second duct being chilled during operation with air flowing through the first duct.

BACKGROUND OF INVENTION

[0001] The present invention relates to a system for providing chilledand super-atmospheric air charge to an engine on a preferential basis.

[0002] Engine designers have devised a potpourri of systems forincreasing the density and decreasing the temperature of the air chargeentering an internal combustion engine.

[0003] For ordinary driving, it is desirable, on only a very infrequentbasis, to operate the engine at its highest possible output. Thus, it isnot desirable or necessary, from the standpoint of cost, fuelconsumption, or weight, to have a system, which is capable of providingdensified and chilled air to the engine on a continuous basis in aquantity sufficient to support the engine's maximum output.

[0004] It is known to provide densifying and even chilling on a basis inwhich the densification and chilling will operate on a continued basis,but such systems, alluded to above, are hampered by excess cost, weight,and power consumption.

[0005] A system according to the present invention overcomes thedisadvantages of prior densification and chilling systems whileproviding excellent throttle response for infrequent accelerations byproviding alternative pathways for air to enter the engine's air supplyplenum. Thus, during normal operation, the air will enter into theunchilled passageway, allowing the chilling apparatus to be pulled downto a very low temperature so as to provide a transient but very highlevel of densification and charge cooling. Because the densificationapparatus does not operate continuously, power consumption of theapparatus is low. Moreover, because chilling is not required to operatecontinuously, a very high level of chilling is available on anintermittent basis, which is consistent with usage of such system fornormal driving.

SUMMARY OF INVENTION

[0006] A charge air management system for an automotive engine includesan air intake plenum for furnishing air to the engine, a first duct forfurnishing air to the intake plenum, and a second duct for furnishingair to the intake plenum. A charge booster increases the quantity of airentering the plenum from the second duct. An intercooler removes heatfrom air flowing through at least the second duct. Finally, a splittervalve controls the relative proportion of air flowing into the plenumfrom the first and second ducts.

[0007] According to the present invention, a charge booster may comprisea supercharger or an exhaust driven turbocharger. If a supercharger isused, it may be driven by a clutched drive.

[0008] According to another aspect of the present invention, thesplitter valve is preferably operated such that the plenum is furnishedwith air flowing through the first duct at relatively lower loads andwith air flowing through the second duct at relatively higher loads.

[0009] The intercooler is preferably cooled with liquid coolant, whichis chilled by an air-to-liquid heat exchanger exposed to ambient air.Liquid coolant may also be chilled by a liquid-to-liquid heat exchanger,which is exposed to a refrigerated fluid. Liquid coolant is chilled bythe air-to-liquid heat exchanger only if the temperature of the liquidcoolant leaving the inner cooler exceeds the ambient air temperature byan amount greater than a predetermined threshold. If the temperature ofthe liquid coolant leaving the intercooler is less than a predeterminedthreshold temperature, a heat exchanger bypass valve will be closed soas to allow the liquid coolant to circulate only through theliquid-to-liquid heat exchanger.

[0010] The refrigerated fluid, which chills the liquid coolant in theliquid-to-liquid heat exchanger, comprises refrigerant fluid flowing ina vehicle air conditioning system. The air conditioning system is calledupon to furnish the refrigerant fluid only if the demand placed upon theair conditioning system is less than a predetermined threshold. In otherwords, if the vehicle occupants demand a high level of air conditioningservice, refrigerant fluid will not be allowed to flow to theliquid-to-liquid heat exchanger.

[0011] As noted above, the flow of charge air through the first andsecond ducts is controlled by a splitter valve, which is itselfcontrolled so as to send most of the air into the plenum through thesecond duct in the event that the throttle associated with the engine isopened at a rate exceeding a threshold opening rate. Similarly, thesplitter valve is controlled so as to send most of the air into theplenum through the second duct in the event that the airflow through theengine exceeds a threshold airflow rate.

[0012] According to another aspect of the present invention, a methodfor operating an automotive engine having a charge air management systemfor furnishing air to an air intake plenum associated with the engineincludes the steps of providing air to the plenum through an uncooledduct during normal operation at lower power levels, providing coolant toa cooled duct during normal operation so as to chill the cooled ductwhen air is being provided to the plenum through the uncooled duct, andproviding air to the plenum through the cooled duct during operation ofthe engine at higher power levels.

BRIEF DESCRIPTION OF DRAWINGS

[0013]FIG. 1 is a schematic representation of an engine having a chargeair management system according to the present invention.

[0014]FIG. 2 is a schematic representation of the various controlelements of the system according to the present invention.

DETAILED DESCRIPTION

[0015] As shown in FIG. 1, engine 8, having air intake plenum 10, isfurnished with intake air by means of first duct 12, which is uncooled,and second duct 14, which is cooled by means of intercooler 18. Splittervalve 20 determines whether air flows into plenum 10 by means of firstduct 12 or second duct 14.

[0016] Air flowing to plenum 10 through duct 14 is subject todensification by means of supercharger 16 and chilling by means ofintercooler 18. Those skilled in the art will appreciate in view of thisdisclosure that supercharger 16 could comprise either a mechanicallydriven supercharger, or an exhaust driven turbocharger, or other typesof screw or vane compressors, or other types of devices known to thoseskilled in the art and suggested by this disclosure.

[0017] In the normal course of events, air enters plenum 10 via firstduct 12 without any additional densification or cooling. If, however,the vehicle driver demands high power output from the engine, thesplitter valve will close and thereby allow air to enter plenum 10primarily through second duct 14.

[0018] During operation wherein air is being allowed to enter plenum 10only through first duct 12, intercooler 18 will be pulled down to alower temperature level by means of liquid coolant which circulatesthrough coolant lines 15 from intercooler 18 through air-to-liquid heatexchanger 22.

[0019] If the ambient temperature within which the vehicle is beingoperated is sufficiently great, heat exchanger bypass control valve 26will be closed so as to allow liquid coolant to circulate only throughliquid-to-liquid heat exchanger 24 and not through air-to-liquid heatexchanger 22.

[0020] The rate of circulation of liquid coolant through lines 15 isdetermined by the operation of coolant pump 34. Coolant pump 34 operatesat a speed which is determined by controller 40 (FIG. 2) as a functionof one or more engine operating parameters. For example, the speed ofcoolant pump 34 may be determined by controller 40 as a function oftemperature of liquid coolant leaving intercooler 18 as determined byintercooler temperature sensor 30. In this case, if the temperature ofthe liquid exceeds a predetermined threshold, pump 34 will be operatedat a higher speed. Alternatively, pump 34 may be operated by controller40 at a speed which is determined by controller 40 as a function of theintake vacuum or, in other words, the air pressure within plenum 10. Inthis case, if air pressure within plenum 10 is at a higher level,indicating that throttle 28 is in an open position, pump 34 may beoperated at a higher speed. Alternatively, the speed of pump 34 may bedetermined in the event that the throttle 28 is opened at very highrate, in which case pump 34 is preferably set at a higher rate of speed.Finally, valves 38 and 39, which control the flow of refrigerantcirculated by compressor 36 through condenser 37, throughliquid-to-liquid heat exchanger 24, and through air conditioningevaporator 32, will be set to bypass evaporator 32 if the present systemis trimmed for maximum performance and if such is sought by thevehicle's driver. Alternatively, valves 38 and 39 may be controlled bycontroller 40 to bypass liquid-to-liquid heat exchanger 24 in the eventthat the present system is trimmed for maximum passenger comfort, and inthe further event that maximum cooling is called for by the vehicle'spassengers.

[0021] The operation of splitter valve 12 is handled by controller 40,with the position of valve 12 depending upon the value of one or moreengine operating parameters. For example, splitter valve 12 may beopened based upon the rate of throttle opening of throttle 28, or in theevent that airflow through the engine is measured by a mass airflowmeter, which is one of sensors 42 of FIG. 2, exceeds a threshold airflowrate. In the case of throttle opening control, if throttle 28 opens at arate exceeding a predetermined threshold, splitter valve 12 will directair through second duct 14. Similarly, if engine airflow exceeds apredetermined threshold, this indicates that the driver is demandinghigher power output, and second duct 14 will be chosen.

[0022] In the event that controller 40 determines that engine load, asdetermined in conventional fashion through the manipulation of data fromits various sensors 42, exceeds its threshold, splitter valve 20 may bepositioned so as to cause air to flow into plenum 10 primarily throughsecond duct 14.

[0023] Finally, according to another aspect of the present invention, apresent method for operating an automotive engine having a charge airmanagement system for furnishing air to an air intake plenum associatedwith the engine operates as alluded to above by providing air to theengine's air intake plenum primarily through an uncooled duct duringoperation at lower power levels, and providing coolant to a secondcooled duct during normal operation so as to chill the cooled duct whenair is being provided to the plenum primarily through the uncooled duct.Air is provided to the plenum primarily through the cooled duct duringoperation of the engine at higher power levels. This cooling is combinedas noted above with the use of a charge booster such as a superchargeror turbocharger, or other type of densification apparatus.

[0024] While the invention has been shown and described in its preferredembodiments, it will be clear to those skilled in the art to which itpertains that many changes and modifications may be made thereto withoutdeparting from the spirit and scope of the invention.

1. A charge air management system for an automotive engine, comprising:an air intake plenum for furnishing air to the engine; a first duct forfurnishing air to the intake plenum; a second duct for furnishing air tothe intake plenum; a charge booster for increasing the quantity of airentering the plenum from the second duct; an intercooler for removingheat from air flowing through at least the second duct; and a splittervalve for controlling the relative proportion of air flowing into theplenum from the first and second ducts.
 2. A charge air managementsystem according to claim 1, wherein said charge booster comprises asupercharger.
 3. A charge air management system according to claim 2,wherein said supercharger is powered by a clutched drive.
 4. A chargeair management system according to claim 1, wherein said charge boostercomprises an exhaust driven turbocharger.
 5. A charge air managementsystem according to claim 1, wherein said splitter valve is operatedsuch that said plenum is furnished with air flowing through said firstduct at relatively lower loads and with air flowing through said secondduct at relatively higher loads.
 6. A charge air management systemaccording to claim 1, wherein said intercooler is cooled with liquidcoolant.
 7. A charge air management system according to claim 6, whereinsaid liquid coolant is chilled by an air-to-liquid heat exchanger whichis exposed to ambient air.
 8. A charge air management system accordingto claim 6, wherein said liquid coolant is chilled by an air-to-liquidheat exchanger which is exposed to ambient air, with said liquid coolantbeing further chilled by a liquid-to-liquid heat exchanger which isexposed to refrigerated fluid.
 9. A charge air management systemaccording to claim 7, wherein said liquid coolant is chilled by anair-to-liquid heat exchanger which is exposed to ambient air, with saidliquid coolant being allowed to flow through the air-to-liquid heatexchanger only if the temperature of the liquid coolant leaving theintercooler exceeds the ambient temperature by an amount greater than apredetermined threshold.
 10. A charge air management system according toclaim 6, wherein said liquid coolant is chilled by a liquid-to-liquidheat exchanger which is exposed to refrigerated fluid.
 11. A charge airmanagement system according to claim 10, wherein said refrigerated fluidcomprises refrigerant fluid flowing in a vehicle air conditioningsystem.
 12. A charge air management system according to claim 11,wherein said liquid-to-liquid heat exchanger is exposed to refrigerantfluid only if the demand placed upon the vehicle air conditioning systemis less than a predetermined threshold.
 13. A charge air managementsystem according to claim 1, wherein said splitter valve is controlledso as to send most of the air into the plenum through the second duct inthe event that a throttle associated with the engine is opened at a rateexceeding a threshold opening rate.
 14. A charge air management systemaccording to claim 1, wherein said splitter valve is controlled so as tosend most of the air into the plenum through the second duct in theevent that the airflow through the engine exceeds a threshold airflowrate.
 15. A charge air management system according to claim 1, furthercomprising a pump for circulating liquid coolant through saidintercooler.
 16. A charge air management system according to claim 15,wherein said pump operates at a speed which is determined by acontroller as a function of one or more operating parameters.
 17. Acharge air management system according to claim 16, wherein said pumpoperates at a speed which is determined by a controller as a function ofthe temperature of liquid coolant leaving said intercooler.
 18. A chargeair management system according to claim 16, wherein said pump operatesat a speed which is determined by a controller as a function of theintake manifold vacuum with which the engine is operating.
 19. Anautomotive engine having a charge air management system, comprising: anair intake plenum for furnishing air to the engine; a first duct forfurnishing air to the intake plenum; a second duct for furnishing air tothe intake plenum; a charge booster for increasing the quantity of airentering the plenum from the second duct, with said charge boostercomprising a supercharger; an air-to-liquid intercooler for removingheat from air flowing through the supercharger and into the plenum, withsaid intercooler being mounted between the supercharger and the plenum;a splitter valve for controlling the relative proportion of air flowinginto the plenum from the first and second ducts; and a coolant systemfor furnishing liquid coolant to said intercooler, with said coolantsystem comprising: an air-to-liquid heat exchanger for rejecting heatfrom the liquid coolant to the ambient; a liquid-to-liquid heatexchanger for rejecting heat from the liquid coolant to a refrigeratedliquid chilled by mechanical means, and a pump for circulating theliquid coolant through the intercooler, the air-to-liquid heatexchanger, and the liquid-to-liquid heat exchanger.
 20. A charge airmanagement system according to claim 19, wherein said splitter valve andsaid pump are operated by an engine controller.
 21. A charge airmanagement system according to claim 20, wherein said controlleroperates said coolant system such that at low engine load, heat will berejected to the liquid-to-liquid heat exchanger while said pump operatesat a lower speed, with said coolant system rejecting heat to the ambientthrough the air-to-liquid heat exchanger at higher engine loads, withsaid pump operating at a higher speed.
 22. A method for operating anautomotive engine having a charge air management system for furnishingair to an air intake plenum associated with the engine, comprising thesteps of: providing air to the plenum primarily through an uncooled ductduring operation at lower power levels; providing coolant to a cooledduct during normal operation, so as to chill the cooled duct when air isbeing provided to the plenum primarily through the uncooled duct; andproviding air to the plenum primarily through the cooled duct duringoperation of the engine at higher power levels.
 23. A method accordingto claim 21, wherein the cooled duct receives air from a charge booster.